THAT statement just made the point i've been trying to make to you for the last 3 pages.......ohc technology is not new.
allison was using ohc before rr i think(although i'm not sure)
No, over head cams certainly isn't new technology, so why you mentioned it in the first place is rather puzzling. I certainly never claimed it was new. If you think I did please quote me.
What part of my post back on page 28 did you not understand?
Pushrod and classic OHC are both obsolete technologies. I'm talking computer controlled variable-timed valves with hydraulic lifters. Some would say that those aren't even "modern" anymore since the japs and euros have been using them since the early 90s. Honda V-Tech, BMW Vanos etc.
my camaro was dyno'd to 820 hp. at 6400 rpm.
sure, you can get that same power from a 2.0 turbotoy. at about 8k to 9k.
why in the world would i want to run an engine that high if i don't have to?
Why in the world would you
not run an engine that high if you
can? How much HP would your Camaro produce if you could safely rev it to 9000 rpm? The answer is a lot more.
the cobra was a completley different car than the ace.
Irrelevant. Both the Ace and the Cobra were designed and produced by AC Cars.
i don't believe you originally said computer controled fuel injection. you only said fuel injection.
You're wrong. Check for yourself and quote me if you think otherwise.
correct. and the body shape and original unmodified frame was.
the drivetrain, powertrain, and suspension(i think) was all ford built.
No it wasn't. Only the engine (and possibly the gear box) was Ford.
"Production proved to be easy, since AC had already made most of the modifications needed for the small-block V8 when they installed the 2.6 litre Ford Zephyr engine, including the extensive rework of the AC Ace's front end. The most important modification was the fitting of a stronger rear differential to handle the increased engine power. A Salisbury 4HU unit with inboard disk brakes to reduce unsprung weight was chosen instead of the old ENV unit. It was the same unit used on the Jaguar E-Type. On the production version, the inboard brakes were moved outboard to reduce cost. The only modification of the front end of the first Cobra from that of the AC Ace 2.6 was the steering box, which had to be moved outward to clear the wider V8 motor.
Badge
The first 75 Cobra Mark I (including the prototype) were fitted with the 260 engine (4.2 L). The remaining 51 Mark I model were fitted with a larger version of the Windsor Ford engine, the 289 in³ (4.7 L) V8. In late 1962 Alan Turner, AC's chief engineer completed a major design change of the car's front end and was able to fit it with rack and pinion steering while still using transverse leaf spring suspension. The new car entered production in early 1963 and was designated Mark II. The steering rack was borrowed from the MGB while the new steering column came from the VW Beetle. About 528 Mark II Cobras were produced to the summer of 1965 (the last US-bound Mark II was produced in November 1964)."
define foe me "valve timing", and what affect it has on horsepower please?
Its effect is that it allows you to run an engine at high RPM without sacrificing low RPM performance. You could safely run your Camaro engine at higher RPM and not having to idle it at 3000.
"In 2001 BMW introduced the Valvetronic system. The Valvetronic system is unique in that it can continuously vary intake valve lift, in addition to timing for both the intake and exhaust valves. The precise control the system has over the intake valves allows for the intake charge to be controlled entirely by the intake valves, eliminating the need for a throttle valve and greatly reducing pumping loss. The reduction of pumping loss accounts for more than a 10% increase in power output and fuel economy."
BLOW DOWN
On the power stroke, the combustion pushes the piston down in the cylinder. During this stroke, it is necessary to open the exhaust valve before the piston gets to the bottom of the cylinder. This will allow the excess pressure in the cylinder to "vent out" just before the piston reaches the bottom of the stroke. The term "Blow Down" is used to describe this event.
Timing the exhaust valve in this manner assures no pressure is left in the cylinder to push against the piston on the exhaust stroke. Otherwise, there could be 20 PSI (or so) pushing against the piston as it starts up the cylinder. This would require some of your engine's power just to push the exhaust out of the cylinder.
High RPM engines need to have the exhaust valve open sooner so the pressure has a better chance to exit the cylinder. However, at lower RPMs, opening the exhaust valve too soon means you didn't take full advantage of the power stroke.
OVERLAP
As the engine cycles, there is a period when both the intake and exhaust valves are open at the same time. This valve timing is known as "overlap." Think of this as the exhaust and intake cycles overlapping each other.
The valves are timed so the intake valve opens slightly before the piston reaches top dead center (TDC) on the exhaust stroke. Likewise, the exhaust valve is timed to close just after the piston starts down on the intake stroke.
The objective of overlap is for the exhaust gas which is already running down the exhaust pipe, to create an effect like a siphon and pull a fresh mixture into the combustion chamber. Otherwise, a small amount of burned gasses would remain in the combustion chamber and dilute the incoming mixture on the intake stroke. This valve timing is a product of the cam's duration and separation specs. For more information on these cam specs see the Cam Specs & Effects page.
The science involved with overlap is quite complex. Pressures, runner lengths, temperature, and many other aspects influence how well the overlap effect works.
RAM EFFECT
When the piston reaches the bottom of the cylinder on the intake stroke, the intake valve doesn't immediately close at this point. The intake valve remains open even though the piston is starting up the cylinder on the compression stroke. The expression "ram effect" is used to describe this event.
Timing the intake valve in this manner allows an additional amount of fresh mixture to be rammed into the cylinder. The effect is very similar to water hammer in plumbing. What happens is that during the intake stroke the fresh mixture is running fast enough down the intake manifold and into the cylinder that it can not instantly stop when the piston stops at the bottom of the intake stroke. Just like the water hammer effect, the incoming mixture is rammed into the cylinder even though the piston may be starting up on the compression stroke.
High RPM engines can have the intake valve remain open longer to take advantage of this ram effect. However, at low RPMs, the ram effect is not strong enough and the piston will start to push the fresh mixture back out of the cylinder. Of all the different valve timing effects, this one can have the greatest impact on your engine's performance.
i just stopped by my old boss's shop the other night. he had his 2006 F650 tow truck up on stands. seems the turbo blew. the thing only has 120k on it too.
Then why didn’t he change it before it blew? Doesn’t Ford have a replacement interval on their turbos? I think that’s pretty common now. Turbos wear out just like fan belts and brake pads.
Die Hard is the type of person that doesn't get his hands dirty and pays others to do it.
You're absolutely right about that, even if it’s quite irrelevant.
